Radiocircuit



March 22, 1932. w KAUFMAN 1,850,110

RADIOCIRCUIT Filed March 5. 1927 Patented 1 Mar. i' 272, v1,932` l ytvoLrn'-kAUFMAN,Jor griiRsoN,]NEwJEnsn,.Assignee-iro 1;. immer; or i srms e me Y i fflhiiplication ltiled 'Starch' 5,

zV provision of afseriesyoff :three Aelectrodeaudionsrandtheir,associated circuits connected in Vcascade v:to (form aradio-'frequency `am.;- pliieranda detector. A still .-furthenobjeet of`this invention 'is :2c tofprovidefresistance connections between .the

input, .circuits .of each Vaudion rof a. radio yfrequencyamplier .and aresistance connection` between-.fthe input or outputcirouit of .thedetector tube and the. finput, circuit vof .the preceding ampliiiertube.

fully-sought by l,means oithe arrangement disclosedzhereinafter. .I I -fThis invention resides substantiallyiin-:the combination, arrangement',location and circuitarlvconnections` ofthe yvarious elements as`Willtbe;completely vdescribed below. v The single :ligure :in ithe'drawing ,isy a diagrammatic illustrationwof the relative .are rangement,of-the parts ftoigprovide -:my invention. y t

Since the advent of radio frequency ampli fiers employing ithe "well:known three gelectrode 4*audionfit `hasbeen'fthe-laim ,of those skilledinkthe art `to provideay simple tandf ef-V cient means :for preventingfintercircuit .reaction which 'isk productive ofdisturbing.oscillations. In practical operation a multi-` stage ptuned -radiolfrequen cyf amplifier :isy sub ject fto .the iproduction" ofyundesirable voscillations'because ofthe/capacity coupling between therinput :and joutput :circuitsj of each stageV :through the vinherent 1'capacity ibetweenzthej opiate. andigrid' :ofth'e audion tubes generallyemployedin su'chfcircuits. :Lhave These -and man 'A other obj ect-s aresuccess-ff devised. la relatively simple ,circuit :Eor

vontngor supprossngthe proluoton ofimr. desirablecurrents in ttheinputzcircuitof each Stage of the radio frequency amplifier. by voor son.ofthe reactionoftbe outputcurrentgupon Referring to the drawing,l theantenna groundsystem is shown oomprisingtheeverhoadnotwork l, tholplmoryofotransformor 2, andthe groundgat 3. The ls*eco/ndary-o-thetothegroundlead andltolthefilament .8 ogtlie first audionf -A variablecondenser y.5 isV shunted across the inductanc x4 ifOI ,the lpurpcw seoftuning .the .grid-filamentcircuitof the first u audion :to .the'frequency of the `iinconning Water-A high resistance sfoonnootodfbol'loA tween Vthe vgid and .lomont .and provdooiia leakagopoththerebetween Lhowe 'found thata leak `of three megohms issuitable fiorthisggpurpose. jflhe plate;` Q/fris connected through tho primary of :a.iredozffroquenoy :transformer l0 .whiehhas vone terminal connectedvtoxtheV positive 'side of the "B battery source.-297 the secondary l1.being shuntedby the @condenser y l2 .and comprising gthe tuned inputcircuit of the -second iaudion. -One -terf minal ofthisftunedinputcircuit isv connected to ,the grid 14 ,and its other terminal is econ-f.nected to vtheilamen't 15. A high resistance grid yleak 13 is kconnectedlbetween the ygrid and filament andmay` have a value vof 1the order )oftwo megohrns. Theplate L6 in nthe second audionfs connected through the`prmary 1'7 'of Va radio Lfrequency `trarisjioltmer Vwhich has its otherterminal connectedto the tector tubo ondono termino-'1 ofthe llairlorit24. A grid condenser y21- and'ygrid leakf22 to transformerfsShoWnatA-:nd has .onolterm-f naliconnected to the. grid .Tof thev firstaudion; and Iits other lterminal connected bothy 'we y ofthe usualconstruction. is 4shown in Vthe grid lead. A high variable '.,resistance20 a resistance 3l of the order of five megohms,

denser of a value of .O02l micro-farads isv shunted across the soundreproducing device 27j. HThe terminals of lall the cathodes or filamentsare connectedV in parallel through of supply 33. The grids of the firstand second audions are connected together through and the grid of thesecond audion or radio frequency amplifier is connected to the gridofthe detector tube through a resistance 324 It is at once apparent tothoseskilled in the i art that many changes in the details ofarrangement of the parts` will readily occur without departing from thescope of this invention. For example, while I have disclosed theinvention as applied to a 2-stage radio frequency amplier-and a detectorit is, of course, true that the principles of the invention may beapplied to amplifiers of anynumber of stages. kWhile I have shown noaudio-A frequency stages connected to the radio-frequency amplifiers anddetector it is clearly evident that instead of connecting a soundreproducing device in the output circuit of the detector tube that theoutput terminals could be connected to the input of a multistageaudio-frequency amplifier. It will be further evident that the variousvalues of resistance and capacity which I have disclosed as desirablecan be varied to suit particular conditions without departing from thespirit and scope of this invention. I also contemplate within the scopeof `this disclosure to include a connection between the grid of the lastradio frequency amplifier and the plate of the detector rather than thegrid of the detector if this is found desirable since Iliave discoveredthat fairly satisfactory operation is secured thereby.

I do not, therefore, desire to be particularly restricted to thedisclosure in the drawing and specification which have been given forthe purposes of illustration, but rather to the ieldof my invention as Idefine it in the appended claims.

g cluding resistances only. the variable resistance 34 to a suitablesourceV What I seek to secure by United States Letters Patent is:

1. In a radio receiving system the combination with a plurality of threeelectrode audions each including a grid, a plate and filament, an inputcircuit for each audion including grid and filament and an outputcircuit for each audion including plate and lament, of a seriesconnection between each grid iii- 2'. In a radio signalling system thecom- .bination with a plurality of three electrode audions each having agrid, plate and lament` and-.their associated circuits arranged toprovide a cascade yamplifier of aconnection between each set ofelectrically adjacent grids including a high resistance only whereby allthe grids are in series. Y

3. In a radio signalling system the combination with a plurality ofthree electrode audions each having a grid, plate and filament and theirassociated circuits arranged to provide a cascade connected multi-stageamplifier and a detector, of a resistance connection between eachelectrically adjacent grid and a Vresistance connected between the gridof the last amplifier and the grid of the detector tube all of saidgridsbeing electrically in series. Y

4. In a multi-stage Vaudion receiving circuit comprising a plurality ofradio frequency amplifiers and a detector of a resistance connectionbetween the grid and filament of each `audion and a resistanceconnection between the grids of all the amplifiers and between the gridof the last radio'frequency amplifier and the gridof the detector.

5. In a radio circuit the combination with an audion amplier stage andan audion detector, said audions having three electrodes, and circuitsassociating said audions into an operative circuit of a seriesconnection including resistances onlyfbetween the grids of said audions.Y

6. In a radio circuit the combination with an audion amplifier stage andan audion detector, said audions having three electrodes, and circuitsassociating said audions into an operative circuit of an impedanceconnection between the grid of the amplifier audion and the grid of thedetector audion, and" a variable resistance connected between the gridand filament of said detector. f

7. In a radio circuit the combination with an audion amplifier stage andan audion detector, said audions having three electrodes, and circuitsassociating said audions into an operative circuit of a connectionincluding a resistance between the grids of said audions, and a variableresistance connected between the grid and filament ofsaid' detector.

8. In a radio receiving circuitthe combination with a plurality ofaudions each having a plate, grid and filament, said audions beingconnected to form a multi-stage amplifier lil() nd a detector of animpedance connection between the rids of the amplifiers and the grid ofthe eteotor, and an adjustable resistance connected between the grid andfilament of the detector audion.

In testimony Whereoflv have hereunto set my hand on this 28th day oflebruai'y,v A. D.

" WOLFF 'KAUFMAN

